1. Field of the Invention
The invention relates to a control apparatus and particularly relates to a brightness control apparatus and a brightness control method.
2. Description of Related Art
Computers may be categorized into rugged computers and general computers, and the difference is that rugged computers are often used in harsh environments, such as high-temperature or low-temperature environments. Therefore, rugged computers are required to have much higher adaptability to the environmental temperature than the general computers. Factors, such as compactness and light weight, which may be important to general computers, are not the main concerns for rugged computers.
When a rugged computer is operated in a harsh environment, such as at high temperature or low temperature, the brightness of the display may need to be controlled from time to time in order to maintain normal operations of the rugged computer. For example, the brightness of the display needs to be reduced at a high temperature so as to prevent the problem of black screen. For powering on at a low temperature, the brightness of the display needs to be reduced to prevent excessive power consumption (because low-temperature power-on procedure takes more time and the power of other elements needs to be adjusted for heating). In a situation of heavy load, the brightness of the display also needs to be reduced to lower power consumption.
Before the window operating system Windows 8 appears, the brightness of the display is controlled by a pulse width modulation signal outputted by an embedded controller, so as to achieve the aforementioned function of brightness adjustment. However, under the configuration of Windows 8, the brightness of the display is controlled by the Windows Display Driver Model (WDDM). In other words, the brightness of the display is controlled by the pulse width modulation signal outputted by the Platform Controller Hub (PCH) under control of a driver of the Windows Display Driver Model (WDDM). For this reason, the brightness of the display cannot be adjusted by the traditional way in conditions of high temperature, low temperature, or heavy load to maintain normal operation of the computer.